JPH08313912A - Liquid crystal oriented film - Google Patents

Abstract

PURPOSE: To obtain a desired oriented state in a desired area without producing dust by using ion beam irradiating method as an orienting method of a liquid crystal. CONSTITUTION: An org. polymer film formed on a substrate is irradiated with ion beams in vacuum for orientation treatment to obtain a liquid crystal oriented film. In this method, by irradiating the org. polymer film with ion beams, the surface shape and arrangement of polymer chains of the org. polymer film are changed and thereby, orientation of the liquid crystal molecules can be controlled. As for the org. polymer film used, such a material is required that an effect to control orientation by ion beams can be easily obtd. Considering this effect, a polyimide polymer produced by heat treatment of polyamide acid shows good characteristics. As for the ion seed for the ion beams, for example, ion beams of inert gas such as helium, neon and argon are preferably used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment film for a liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal display devices of the twisted nematic system (TN, STN system), which are now widely used, are made of organic materials such as polyimide, polyamide, polyamide-imide, and polyvinyl alcohol in order to arrange liquid crystal molecules in a certain direction. A molecular film is formed on the substrate and its surface is nylon,
The operation is rubbing with a cloth such as rayon or cotton.

However, the alignment treatment by the rubbing operation is
There is a problem that the display quality of the liquid crystal display element is deteriorated due to dust generation, and it is possible to arrange the liquid crystal in a certain direction over the entire surface of the substrate, but it is possible to form regions with partially different alignment states (directions). , Not uniaxial orientation
It is difficult to perform multi-domain orientation, random orientation, amorphous orientation, or the like.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a liquid crystal alignment film which is free from rubbing and does not deteriorate the display quality due to dust generation.
Further, it provides a liquid crystal alignment film in which the alignment state of the liquid crystal is arbitrarily controlled.

[0005]

The present invention is a liquid crystal alignment film characterized by being subjected to alignment treatment by irradiating an organic polymer film formed on a substrate with an ion beam in a vacuum.

By irradiating the organic polymer film with the ion beam, the surface shape of the organic polymer film, the arrangement of the polymer chains, etc. are changed, so that the alignment control of the liquid crystal molecules can be performed. The organic polymer film used for
It was found that the orientation control effect by the ion beam should be easily exhibited, and from this point, it was found that the polyimide-based polymer formed by heat-treating polyamic acid exhibits good properties. Among them, especially pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,4,3 ', 4'-biphenyltetracarboxylic dianhydride, butanetetracarboxylic dianhydride , A polyimide-based polymer formed by heat-treating a polyamic acid having one or more of the acid anhydrides selected from cyclobutanetetracarboxylic dianhydride as an essential component is suitable, and further, A polyimide-based polymer formed by heat-treating a polyamic acid containing an aromatic diamine represented by the formula (1) or a silicone diamine represented by the following formula (2) as an essential component is suitable.

[0007]

Embedded image

(In the formula, R ₁ and R ₂ represent an alkyl group having 1 to 12 carbon atoms or a trifluoromethyl group, which may be the same or different from each other)

[0009]

Embedded image

(Wherein R ₃ is a divalent organic group, m is 1 to 20)
Alignment film used in the present invention, a polyamic acid solution is applied onto a substrate by a spin coating method or a printing method, and if necessary pre-dried in a hot plate or a drying oven, then from 100 ° C. Obtained by heat curing at a temperature of 300 ° C. Examples of the solvent used in the polyamic acid solution include N-methyl-2-pyrrolidone (NMP), dimethylacetamide, dimethylformamide, γ-butyrolactone, diglyme, ethylcarbitol, methylcarbitol, butylcellosolve, diethylene glycol dimethyl ether, dipropylene glycol. Dimethyl ether, xylene, toluene and the like are used alone or in combination. The imidization ratio of the polyimide-based polymer after heat curing is preferably 30% or more, more preferably
50% or more.

The orientation treatment of the formed polyimide polymer is carried out by ion beam irradiation in the present invention. As the ion species of the ion beam, it is preferable to use an ion beam of an inert gas such as helium, neon, or argon.

In the irradiation of the ion beam, it is possible to control the degree of orientational order of the liquid crystal by changing the angle of the irradiation of the ions with respect to the organic polymer film. That is, when the irradiation angle of the ion beam with respect to the organic polymer film is made smaller (the closer the ion beam is parallel to the film surface), the uniaxial orientation of the liquid crystal becomes higher, and the ion beam becomes perpendicular to the organic polymer film. The closer it is, the more random orientation becomes in the macro region. As described above, it is possible to arbitrarily control the alignment state of the liquid crystal by utilizing the fact that the liquid crystal alignment order can be controlled by changing the angle of the ion beam with respect to the organic polymer film. Furthermore, it is possible to change the orientation state of a specific region by using a mask during irradiation of the ion beam.

[0013]

EXAMPLES Examples of the present invention will be described in detail below.
The invention is in no way limited by these examples.

(Synthesis Example 1) 0.1 mol of pyromellitic dianhydride and 250 g of dehydrated NMP were placed in a 500 ml separable flask equipped with a thermometer, a stirrer, a raw material charging port, and a dry nitrogen gas inlet tube, and stirred under a dry nitrogen stream. . While maintaining the temperature of the reaction system at 20 ° C., bisaminopropyltetramethyldisiloxane (in the formula (2), R ₃ is a propylene group, m = 1) 0.03
Mol was added, and then 0.07 mol of 4,4′-diaminodiphenyl ether was further added and stirred for 5 hours to obtain a pale yellow viscous polyamic acid solution.

(Synthesis Example 2) 2,2-bis (4- (4-aminophenoxy) phenyl) propane was used in place of 4,4'-diaminodiphenyl ether as a raw material in the same apparatus and operation as in Synthesis Example 1. A pale yellow viscous polyamic acid solution was obtained.

(Synthesis Example 3) A pale yellow viscous polyamic acid solution was prepared by the same apparatus and operation as in Synthesis Example 1, except that 4,4'-diaminodiphenylmethane was used as a raw material instead of 4,4'-diaminodiphenyl ether. Obtained.

(Synthesis Example 4) 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane was used in place of 4,4'-diaminodiphenyl ether as a raw material by the same apparatus and operation as in Synthesis Example 1. A pale yellow viscous polyamic acid solution was obtained.

(Synthesis Example 5) In the same apparatus and operation as in Synthesis Example 1, 2,3,6,7-
A pale yellow viscous polyamic acid solution was obtained using naphthalenetetracarboxylic dianhydride.

(Synthesis Example 6) The same apparatus and operation as in Synthesis Example 1 were used, and 2,3,6,7-
A pale yellow viscous polyamic acid solution was obtained by using 2,2-bis (4- (4-aminophenoxy) phenyl) propane instead of naphthalenetetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether. .

(Synthesis Example 7) In the same apparatus and operation as in Synthesis Example 1, 2,3,6,7-
A pale yellow viscous polyamic acid solution was prepared by using 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane instead of naphthalene tetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether. Obtained.

(Synthesis Example 8) In the same apparatus and operation as in Synthesis Example 1, 3,4,3 ′, instead of pyromellitic dianhydride was used as a raw material.
A pale yellow viscous polyamic acid solution was obtained using 4'-biphenyltetracarboxylic dianhydride.

(Synthesis Example 9) In the same apparatus and operation as in Synthesis Example 1, 3,4,3 ', instead of pyromellitic dianhydride was used as a raw material
4'-biphenyltetracarboxylic dianhydride, 2,2-bis (4- (4-aminophenoxy) phenyl) propane in place of 4,4'-diaminodiphenyl ether, a pale yellow viscous polyamic acid solution Got

(Synthesis Example 10) In the same apparatus and operation as in Synthesis Example 1, 3,4,
3 ', 4'-biphenyltetracarboxylic dianhydride, 2,2-bis (4- (4- (4-
A pale yellow viscous polyamic acid solution was obtained using aminophenoxy) phenyl) hexafluoropropane.

(Synthesis Example 11) A pale yellow viscous polyamic acid solution was obtained by using butanetetracarboxylic dianhydride instead of pyromellitic dianhydride as a raw material by the same apparatus and operation as in Synthesis Example 1. It was

(Synthesis Example 12) With the same equipment and operation as in Synthesis Example 1, butane tetracarboxylic dianhydride was used instead of pyromellitic dianhydride without using bisaminopropyltetramethyldisiloxane as a raw material. A pale yellow viscous polyamic acid solution was obtained by using 0.1 mol of 2,2-bis (4- (4-aminophenoxy) phenyl) propane in place of 4,4'-diaminodiphenyl ether.

(Synthesis Example 13) With the same equipment and operation as in Synthesis Example 1, butane tetracarboxylic dianhydride was used instead of pyromellitic dianhydride without using bisaminopropyltetramethyldisiloxane as a raw material. A pale yellow viscous polyamic acid solution was obtained by using 0.1 mol of 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane instead of 4,4'-diaminodiphenyl ether.

(Synthesis Example 14) With the same apparatus and operation as in Synthesis Example 1, butane tetracarboxylic acid dianhydride was used instead of pyromellitic dianhydride without using bisaminopropyltetramethyldisiloxane as a raw material. A pale yellow viscous polyamic acid solution was obtained by using 0.1 mol of each of 4,4'-diaminodiphenylmethane instead of 4,4'-diaminodiphenyl ether.

(Synthesis Example 15) A pale yellow viscous polyamic acid solution was obtained by using cyclobutanetetracarboxylic acid dianhydride instead of pyromellitic dianhydride as a raw material in the same apparatus as in Synthesis Example 1.

(Synthesis Example 16) Cyclobutanetetracarboxylic acid dianhydride was used in place of pyromellitic dianhydride and 2,2-bis instead of 4,4'-diaminodiphenyl ether as raw materials in the same apparatus as in Synthesis Example 1. A pale yellow viscous polyamic acid solution was obtained using (4- (4-aminophenoxy) phenyl) propane. (Synthesis Example 17) Cyclobutanetetracarboxylic acid dianhydride was used instead of pyromellitic dianhydride as a raw material in the same apparatus as in Synthesis Example 1, and 2,2-bis (4- Using (4-aminophenoxy) phenyl) hexafluoropropane, a pale yellow viscous polyamic acid solution was obtained.

Example 1 The NMP solution of the polyamic acid obtained in Synthetic Example 1 was treated with NMP so that the polyamic acid concentration was 6%.
Was diluted with and applied onto ITO of a glass substrate with ITO by spin coating, and baked at 200 ° C. in a hot air oven to form a polyimide film of 500 nm. Next, an argon ion beam of 300e is applied to this polyimide film so as to form an angle of 15 degrees from the substrate.
Irradiation was performed with an acceleration voltage of V 2. After that, without performing any particular cleaning treatment, the two substrates were bonded together with a gap of 6 μm so that the ion beam irradiation direction was twisted by 90 °, and nematic liquid crystal (Merck, ZLI-2293) was injected to assemble a TN cell. . When the alignment state of the liquid crystal was observed, the entire surface showed good uniaxial alignment, and no disorder of the liquid crystal alignment was observed even after the treatment at 120 ° C./500 hours.

Example 2 The polyamic acid obtained in Synthesis Example 1 was diluted, coated and baked in the same manner as in Example 1 to form a coating film. Next, the entire surface of the polyimide film is irradiated with an ion beam from a direction perpendicular to the substrate, and then a mask is formed so that half of the substrate is not irradiated with the ion beam. Irradiation was performed. The two substrates were bonded to each other with a gap of 6 μm so that the regions irradiated with the ion beam at the angle of 10 ° face each other and the direction of the ion beam irradiation was 90 °, and the nematic liquid crystal (Merck, ZLI -2293) was injected to assemble a TN cell. Observing the alignment state of the liquid crystal, the region where the ion beam was vertically irradiated was random alignment, and the region where the ion beam was irradiated to the substrate at an angle of 10 degrees showed good uniaxial alignment. It was oriented.

(Example 3-20) The polyamic acids shown in Synthesis Examples 1 to 17 were used alone or in combination of two or more thereof, and diluted, coated and baked in the same manner as in Example 1 to form a coating film. Further, an ion beam irradiation treatment was carried out in the same manner as in Example 1 to assemble a liquid crystal cell, and the alignment state of the liquid crystal was observed. The results are shown in Tables 1 and 2.

[0033]

[Table 1] * 1 Indicates the synthesis example number

[0034]

[Table 2] * 1 Indicates the synthesis example number. In case of mixed system, the weight ratio is shown in parentheses.

Comparative Example Similar to Example 1, the polyamic acid synthesized in Synthesis Example 1 was applied to a substrate and baked to form a coating film. As the alignment treatment, rubbing with a cotton cloth was performed instead of ion beam irradiation, and the liquid crystal was injected by laminating without washing. As a result, contaminants (dust), which are considered to be caused by rubbing, were present in several places, and disorder of liquid crystal alignment was observed.

[0034]

In the present invention, when the polyamic acid is used as the alignment film, the ion beam irradiation method is used as the alignment treatment method for the liquid crystal, so that dust generation which is a problem in the rubbing method which is the conventional alignment treatment is caused. It is possible to form an arbitrary alignment state in an arbitrary region.

Claims (5)

[Claims] 1. A liquid crystal alignment film, which is subjected to alignment treatment by irradiating an organic polymer film formed on a substrate with an ion beam in a vacuum. 2. The liquid crystal alignment film according to claim 1, wherein the organic polymer film formed on the substrate is a polyimide-based polymer formed by heat-treating polyamic acid on the substrate. 3. The organic polymer film formed on the substrate is pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,4,3 ′, 4′- Biphenyltetracarboxylic dianhydride, butanetetracarboxylic dianhydride, a polyimide-based polymer formed by heat-treating a polyamic acid containing an acid anhydride as an essential component selected from cyclobutanetetracarboxylic dianhydride The liquid crystal alignment film according to claim 1. 4. The organic polymer film formed on the substrate is a polyimide-based polymer formed by heat-treating a polyamic acid containing a diamine selected from the following formula (1) as an essential component. The liquid crystal alignment film described. Embedded image (In the formula, R ₁ and R ₂ represent an alkyl group having 1 to 12 carbon atoms or a trifluoromethyl group, which may be the same or different from each other) 5. The organic polymer film formed on the substrate is a polyimide-based polymer formed by heat-treating a polyamic acid containing diamine represented by the following formula (2) as an essential component. The liquid crystal alignment film described. Embedded image (In the formula, R ₃ is a divalent organic group, m is an integer of 1 to 20)